How was the "IBS" diagnosed, and how was the diagnosis of internal haemorrhoids made? Have you had any tests in the hospital (i.e. endoscopies)? The appointment may well be to see if there is anything else going on (like inflammatory bowel disease), and get an expert (i.e. colorectal surgeon) rather than the GP to make this diagnosis
If they are simple haemorrhoids (which can be diagnosed with a simple 'scope done in clinic), they may be able to band them then and there. If it turns you need an operation for it, you'll likely be on a relatively long waiting list for this do be done electively, and you can specify dates you can't make, or ask to be referred (via your GP as Helen says) to a hospital closer to home if possible.
I'd go to the appointment if only to find out what's going on to be honest.
COI: surgical trainee